Roof coatings may be used to add a layer of protection to a roof or one or more roof surfaces, such as to provide protection from various elements, which may act to penetrate or erode a roofing surface. Roofing coatings may serve as moisture barriers, UV ray barriers, thermal barriers, wind barriers, or other protection barriers to reduce or eliminate penetration by an element into or through one or more roofing surfaces.
Liquid roof coatings may be applied over a roofing surface by application techniques such as spray, brushed on, and/or roller application. Roofing surfaces may commonly be composed of asphalt shingles, aluminum, steel or other metal materials, asphalt membranes, polymer modified asphalt membranes or other roofing materials. A roof coating may be applied over the roofing surface one or more times to add additional barrier protection to the roofing surface.
Asphalt roof coatings are known. Asphalt cutback is a desirable material in a roof coating because it may be applied cold so as not to require work with hot material in the application. However, virgin asphalt can be costly. Using recycled asphalt materials, such as scrap asphalt shingles, as a replacement for part of the virgin asphalt in a roof coating could be beneficial in that the scrap materials are less costly and may improve performance. Employing recycled scrap asphalt shingle materials is also beneficial in that the non-asphalt components of the scrap shingles, such as but not limited to, limestone, granules and glass fiber, may act as fillers in a roof coating product and reduce or eliminate the need to add other fillers to a roof coating composition of matter. The glass fiber may also add some reinforcing qualities to the roof coating. However, the scrap shingles must be processed or ground into a small enough size to be capable of being suspended in a roof coating product, such as approximately 20-40 mesh or smaller.
Prior attempts to salvage asphalt in recycled materials have been cost prohibitive, requiring many processing steps and costly machinery, and have often attempted to recover the asphalt in pure form, which has required separating it from other materials in the recycled scrap, again making the process complicated and costly. Some methods require wet processing the scrap shingle in a liquid and/or by applying heat. Other methods have included use of hammer mills, but have produced scrap asphalt that is not of a sufficiently small size to be suitable for a roof coating application, and which is instead suitable primarily for paving products. There has been lacking in the art a method of dry processing recycled scrap asphalt shingle to a size sufficiently small for roof coating applications without heating or significant cooling.
For example, U.S. Pat. No. 4,222,851 to Good teaches a method of recovering asphalt and other materials from scrap shingles by solvent extraction. Good '851 teaches that a hammer mill is used to grind the scrap shingles to a 3″×3″ size and then liquid solvents are applied with heat to chemically reclaim asphalt in the shingles. Good '851 does not teach a dry processing method resulting in ground shingle powder of a sufficiently small size to be suitable for a roof coating, nor any roof coating products.
Asphalt shingles have been recycled into pavement products. U.S. Pat. No. 4,706,893 to Brock teaches a hammer mill that grinds recycled asphalt shingles to a size of ¼ inch or ⅛ inch. They are heated to melt the asphalt contained therein. Liquid asphalt is added to the heated particles after they are ground. However, there is lacking a method of processing recycled asphalt shingles without adding liquid asphalt to them or heating them, and there is lacking a resulting ground product of a sufficiently small mesh size to be suitable for a roofing coating.
U.S. Pat. No. 5,236,497 to Grzybowski teaches a solid cold patch roadway repair product having recycled scrap asphalt shingle added as a minor additive to the composition. However, Grzybowski does not teach a roof coating product, nor does it teach a process by which recycled scrap shingle is ground.
U.S. Pat. No. 5,385,426 to Omann teaches a two hammer mill apparatus for recycling scrap asphalt shingle into a paving product. The shingle may be sprayed with water prior to entering the first hammer mill and also within the hammer mill. The water must later be removed by heating. The resulting product is not of sufficiently small size to be suitable for a roof coating product.
Attempts have been made to incorporate recycled scrap asphalt materials into roofing surface products. Most shingles are suitable, once ground, to incorporate into roof coatings. Size matters as if it is too large, small lumps are evident in the roofing product, which are not desirable.
U.S. Pat. No. 6,290,152 to Zickell teaches a method of recycling asphalt based material by heating it in a mill. Zickell '152 teaches that the recycled shingle is wet processed in a ball mill. Zickell '152 teaches that the scrap asphalt product, such as shingle, is simultaneously heated and milled in a heated milling apparatus in liquid to reduce the asphalt material including granules to a fine mesh in suspension in liquid asphalt. The milling apparatus has rods or paddles to pull the recycled asphalt under and into the liquid slurry, and a filter apparatus for filtering reduced asphalt and removing foreign objects therefrom. Although Zickell '152 claims to produce particles of a sufficiently small size for roofing surface applications, it requires heat and wet processing. It also teaches that pure asphalt and/or solvents are added to the recycled materials prior to milling: virgin, non-oxidized asphalt, aromatic rich asphalt, flux asphalt, solvents, oil or a combination of any of these is added to the recycled mixture to rejuvenate the mixture of recycled asphalt and to keep it liquid during processing. There is lacking a method and apparatus for dry processing scrap asphalt materials for a roof coating product. There is lacking in the art a process for processing scrap asphalt materials for a roof coating without adding pure asphalt and/or solvents to the recycled materials in the milling.
Similarly, U.S. Pat. No. 5,098,025 to Drouin teaches processing scrap asphalt shingle in a liquid mixture to grind it to about a 10 mesh particle size and using the wet paste mixture containing ground asphalt and/or other ground materials from the recycled shingles (such as rock or glass), in solid paving or roofing products. Drouin teaches that liquid in the slurry mixture acts to separate asphalt and other particles. Drouin teaches that the shingles are processed wet by grinding them with liquid (water or a solvent) to prevent the particles from heating and clumping together. However, Drouin teaches away from a dry powder product made with dry processing from recycled scrap shingles, and states that dry processing creates too much heat and particle clumping, which is solved by its wet processing.
U.S. Pat. No. 6,228,503 to Zickell teaches a roll roofing surface material made in part of recycled scrap shingles. However, Zickell '503 teaches that flux asphalt must be added to the reclaimed materials to achieve requisite viscosity to allow for pumping. The recycled materials are reclaimed by using the process of U.S. Pat. No. 5,848,755 to Zickell, which reclaims asphalt in liquefied form and shreds them in a ball mill to 250-300 mesh size during this wet processing. There is lacking a method and apparatus for dry processing scrap asphalt materials for a roof coating product. There is lacking in the art a process for processing scrap asphalt materials for a roof coating without adding pure asphalt to the recycled materials in the milling.
Harmon US2010/0064937 teaches a method of recycling scrap asphalt shingle in a single hammer mill process requiring heat to be added to the material for processing. The material is heated and liquefied to produce a slurry that can be formed into a finished product.